Hierarchical HZSM-5 for Catalytic Cracking of Oleic Acid to Biofuels

Solid acid catalyzed cracking of waste oil-derived fatty acids is an attractive route to hydrocarbon fuels. HZSM-5 is an effective acid catalyst for fatty acid cracking; however, its microporous nature is susceptible to rapid deactivation by coking. We report the synthesis and application of hierarchical HZSM-5 (h-HZSM-5) in which silanization of pre-crystallized zeolite seeds is employed to introduce mesoporosity during the aggregation of growing crystallites. The resulting h-HZSM-5 comprises a disordered array of fused 10–20 nm crystallites and mesopores with a mean diameter of 13 nm, which maintain the high surface area and acidity of a conventional HZSM-5. Mesopores increase the yield of diesel range hydrocarbons obtained from oleic acid deoxygenation from ~20% to 65%, attributed to improved acid site accessibility within the hierarchical network.

Altering fiber density of cockscomb-like fibrous silica-titania catalysts for enhanced photodegradation of ibuprofen

Fibrous silica-titania (FST) catalysts were synthesized by microemulsion followed by silica seed-crystal crystallization methods under various molar ratios of toluene to water (T/W). The catalysts were characterized by XRD, UV-DRS, FESEM, TEM, AFM, N₂ adsorption-desorption, FTIR, and ESR. The results revealed that altering the T/W ratio affected the growth of the silica and titania and led to different size, fiber density, silica-titania structure, and number of hydroxyl groups, as well as oxygen vacancies in the FSTs, which altered their behavior toward subsequent application. Photodegradation of ibuprofen (IBP) are in the following order: FST(6:1) (90%) > FST(5:1) (84%) > FST(7:1) (79%) > commercial TiO₂ (67%). A kinetics study using Langmuir-Hinshelwood model illustrated that the photodegradation followed the pseudo-first-order and adsorption was the rate-limiting step. Optimization by response surface methodology (RSM) showed that the pH, initial concentration, and catalyst dosage were the remarkable parameters in photodegradation of IBP. The FST (6:1) maintained its photocatalytic activities for up to five cycles reaction without serious catalyst deactivation, and was also able to degrade other endocrine-disrupting chemicals, indicating its potential use for the treatment of those chemicals in wastewater.

Further Insight into the Definite Morphology and Formation Mechanism of Mesoporous Silica KCC-1

The unique three-dimensional pore structure of KCC-1 has attracted significant attention and has proven to be different compared to other conventional mesoporous silica such as the MCM-41 family, SBA-15, or even MSN nanoparticles. In this research, we carefully examine the morphology of KCC-1 to define more appropriate nomenclature. We also propose a formation mechanism of KCC-1 based on our experimental evidence. Herein, the KCC-1 morphology was interpreted mainly on the basis of compiling all observation and information taken from SEM and TEM images. Further analysis on TEM images was carried out. The gray value intensity profile was derived from TEM images in order to determine the specific pattern of this unique morphology that is found to be clearly different from that of other types of porous spherical-like morphologies. On the basis of these results, the KCC-1 morphology would be more appropriately reclassified as bicontinuous concentric lamellar morphology. Some physical characteristics such as the origin of emulsion, electrical conductivity, and the local structure of water molecules in the KCC-1 emulsion were disclosed to reveal the formation mechanism of KCC-1. The origin of the KCC-1 emulsion was characterized by the observation of the Tyndall effect, conductometry to determine the critical micelle concentration, and Raman spectroscopy. In addition, the morphological evolution study during KCC-1 synthesis completes the portrait of the formation of mesoporous silica KCC-1.

Surface modification of banana stem fibers via radiation induced grafting of poly(methacrylic acid) as an effective cation exchanger for Hg(ii)

A low cost adsorbent, banana stem fibers (BSFs), was used for modification by grafting with methacrylic acid via three free radical generation methods.

Catalyzed Claisen–Schmidt reaction by protonated aluminate mesoporous silica nanomaterial focused on the (E)-chalcone synthesis as a biologically active compound

The energy saving HAlMSN catalyzed Claisen–Schmidt reaction for (E)-chalcone synthesis with high yield, low temperature, short reaction time and catalyst reusability.

Synthesis and characterization of fibrous silica ZSM-5 for cumene hydrocracking

Fibrous silica ZSM-5 (FZSM-5) with a novel dendrimeric morphology was synthesized using a CTAB-based microemulsion system. The dendrimers increased the active site accessibility and enhanced the catalytic activity for large molecule hydrocracking and ethylbenzene dehydrogenation.

Dispersive solid phase extraction of gold with magnetite-graphene oxide prior to its determination via microwave plasma-atomic emission spectrometry

In this paper we demonstrated the quantitative analysis of gold in environmental water samples using microwave plasma atomic emission spectrometry (MP-AES) after dispersive solid phase extraction (DSPE) on magnetite graphene oxide (m-GO).

Interaction between copper and carbon nanotubes triggers their mutual role in the enhanced photodegradation of p-chloroaniline

Copper (Cu, 1–5 wt%) was loaded onto carbon nanotubes (CNTs) by a simple electrochemical method.

Synergistic interactions of Cu and N on surface altered amorphous TiO2 nanoparticles for enhanced photocatalytic oxidative desulfurization of dibenzothiophene

Amorphous TiO₂ (AT) nanoparticles were prepared by a simple sol–gel method and subsequent incorporation with 5–20 wt% copper via an electrochemical method in the presence of tetraethylammonium perchlorate gave an active CuO/TiO₂ (CAT) photocatalyst.

Copper oxide supported on graphene for phodegradation of rhodamine B

In recent years, dyes are one of the major sources of the water contamination that lead to environmental problems. For instance, Rhodamine B (RhB) which was extensively used as a colorant in textile industries is toxic and carcinogenic. Among many techniques, photocatalytic degradation become the promising one to remove those dyes from industrial wastewater. Recently, graphene has shown outstanding performance in this application due to its intrinsic electron delocalisation which promotes electron transport between composite photocatalyst and pollutant molecules. While, copper oxide (CuO) is well-known has a lower bandgap energies compared to other semiconductors. Therefore, in this study, copper oxide supported on graphene (CuO/G) was prepared and its photocatalytic activity was tested on degradation of RhB. The catalysts were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. The results showed that the interaction between copper and graphene support could enhance the photocatalytic activity. The 5 wt% CuO/G was found to give the highest degradation (95%) of 10 mg L-1 of RhB solution at pH 7 using 1 g L-1 catalyst after 4 hours under visible light irradiation. The photodegradation followed the pseudo first-order Langmuir-Hinshelwood kinetic model. This study demonstrated that the CuO/G has a potential to be used in photocatalytic degradation of various organic pollutants.

Photocatalytic decolorization of methylene blue using zinc oxide supported on mesoporous silica nanoparticles

Various dyes that are used in textile, paper, cosmetics and plastics industries may produce harmful effects on the health of living organisms and the environment if not treated properly before being discharged into water bodies. Among many techniques, photocatalytic process is one of the promising treatment for these dyes. Zinc oxide (ZnO) is well-known comparable with TiO2 due to its unique properties and numerous advantages. While, mesoporous silica nanoparticles (MSN) is an excellent solid support for heterogeneous catalysts due to its high surface area, thermal and mechanical stability, highly uniform pore distribution, tunable pore size, and unique hosting properties. Therefore, in this study, ZnO/MSN (ZM) catalysts were prepared and its physicochemical properties was characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The catalyst was tested on the photodecolorization of methylene blue (MB) dye. The results showed that the interaction between ZnO and MSN support could enhanced the photocatalytic activity. The 0.5 g L-1 of 5ZM was found to give the highest degradation (80 %) of 10 mg L-1 of MB solution at pH 7 after 3 h under UV light irradiation. The photodecolorization followed the pseudo first-order Langmuir-Hinshelwood kinetic model. This study demonstrated that the prepared 5ZM has a potential to be used in photocatalytic degradation of various dyes as well as organic pollutants.

Elucidation of acid strength effect on ibuprofen adsorption and release by aluminated mesoporous silica nanoparticles

Mesoporous silica nanoparticles (MSN) with 1–10 wt% loading of aluminum (Al) were prepared and characterized by XRD, N₂ physisorption, ²⁹Si and ²⁷Al NMR, FT-IR and FT-IR preadsorbed pyridine.

CO2 reforming of CH4 over Ni/mesostructured silica nanoparticles (Ni/MSN)

Higher basicity of Ni/MSN suppressed the formation of deactivated carbon and contributed to a good stability in CO₂ reforming of CH₄.

Synthesis of dual type Fe species supported mesostructured silica nanoparticles: synergistical effects in photocatalytic activity

Dual type Fe species (isomorphously substituted Fe species and a colloidal α-FeOOH (IS-FeOOH)) supported on mesostructured silica nanoparticles (IS-FeOOH/MSN) were prepared by a simple electrochemical method followed by impregnation.

Grape-like mesostructured silica nanoparticle-decorated single-walled carbon nanotubes: silica growth and dye adsorptivity

Single-walled carbon nanotube (SWCNT)-mesostructured silica nanoparticle (MSN) adsorbents (S-MSNs) were prepared through a simple one-step method with various loadings of SWCNTs.

High activity of aluminated bifunctional mesoporous silica nanoparticles for cumene hydrocracking and measurement of molar absorption coefficient

Pt/HAlMSN synthesized with Si/Al ratios = 7–50 showed high activity in cumene hydrocracking due to the Brønsted and Lewis acid sites.

New insights into self-modification of mesoporous titania nanoparticles for enhanced photoactivity: effect of microwave power density on formation of oxygen vacancies and Ti3+ defects

Mesoporous titania nanoparticles (MTN) were successfully prepared by a microwave (MW)-assisted method under various power densities.

Acid-vacuo heat treated low cost banana stems fiber for efficient biosorption of Hg(ii)

HCl treatment on Banana Stem Fiber (BSF) increased the cellulose accessibility. Prior to the biosorption process, the biosorbent was activated in vacuo at 373 K. The activation improved the maximum Hg(ii) biosorption capacity from 28 to 372 mg g⁻¹.

Nickel-promoted mesoporous ZSM5 for carbon monoxide methanation

Synergistic effect of Ni and the mZSM5 support led to high methanation activity of Ni/mZSM5. Two possible reaction routes emerged: (1) adsorbed CO may be reacted with H₂ to form CH₄ and H₂O; (2) adsorbed H may be reacted with CO to form CH₄ and CO₂.

Chromium oxide zirconia solid acid catalyst for n-pentane isomerization

New catalyst based on zirconia (ZrO2) supported by chromium oxide (CrO3) for isomerization of n-pentane was studied. CrO3-ZrO2 was prepared with chromium nitrate by the titration and sol-gel technique. The physical properties of the catalysts were characterized by XRD, BET surface area analyzer, and TEM. The acidity and structure of catalysts were determined by pyridine and lutidine preadsorbed FTIR spectroscopy.  The isomerization of n-pentane was carried out at 523 K under hydrogen stream. CrO3-ZrO2 shows the differences in terms of physical properties where the introduction CrO3 partially eliminated the monoclinic phase of ZrO2 and developed new peaks assigned to tetragonal phase of ZrO2. CrO3-ZrO2 also shows a higher specific surface area where it increases in the pore volume of the catalyst compare to its parent zirconia.  The IR results indicated that CrO3-ZrO2 catalyst have strong Lewis and weak Brønsted acid sites. The conversion of n-pentane for CrO3-ZrO2 was 32% respectively, while the selectivity to iso-pentane was 100%. ________________________________________GRAPHICAL ABSTRACT

Photoisomerization of n-pentane over nano ZnO/MoO3-ZrO2

A series of nano ZnO/MoO3-ZrO2 catalysts with different ZnO loading (1.0, 2.5, 5.0 wt%) were prepared by impregnation method for n-pentane photoisomerization under hydrogen or nitrogen atmosphere. The properties of the catalysts were characterized with X-ray Diffraction (XRD), Brunauer Emmett Teller (BET), Transmission Electron microscope (TEM) and FTIR. The XRD result showed that the fraction of tetragonal phase of ZnO/MoO3-ZrO2 was about 0.67 for all samples. While, the specific BET surface area was about 24 m2/g. Pyridine adsorbed FTIR results showed that all samples possessed high concentration of strong Lewis acid sites and small concentration of weak Bronsted acid sites. The interaction of hydrogen and surface samples at 298-523 K formed protonic acid sites with the concomitant of the partial elimination of Lewis acid sites. Whereas no changes of the concentration of acid sites were observed in the presence of nitrogen atmosphere. The activity of all samples in the n-pentane photoisomerization was strongly determined by the presence of hydrogen gas. In fact no activity was observed in the absence of hydrogen________________________________________GRAPHICAL ABSTRACT

Facile synthesis of a zinc oxide nanoparticle by electrochemical method

An electrogenerated zinc oxide (EGZnO/Naph) nanoparticle was successfully synthesized by electrolysis of a N,N-dimethylformamide (DMF) solution containing naphthalene and a supporting electrolyte in a one-compartment cell fitted with a platinum cathode and a zinc anode. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies showed that the EGZnO/Naph consists of pure single crystalline wurtzite of hexagonal structure with average diameters of 10-15 nm. The BET surface area of the EGZnO/Naph was 65 m2/g, which is 15 times larger than that of commercial ZnO powder. The zinc oxide was also confirmed by Fourier transform infrared (FTIR) results which showed vibrational bands at 500 and 434 cm−1. Furthermore, the absorption peak of the EGZnO/Naph obtained at 366 nm (3.35 eV), is very close to the band gap of the ZnO 1s–1s electron transition (3.37 eV). Based on these results, this study reports a new pathway to synthesize nanosize of ZnO particle using a simple electrochemical process.________________________________________GRAPHICAL ABSTRACT

Photodecomposition of methylene blue over EGZrO2/HY in aqueous alkaline solution

The photodecomposition of methylene blue (MB) in an aqueous alkaline solution over EGZrO2/HY catalyst was investigated. The prepared catalyst was examined using X–ray diffraction (XRD) and transmission electron microscopy (TEM). The MB was completely decolorized under visible light at pH 11 after 432 h over 1 wt% EGZrO2/HY photocatalyst. Photolysis almost did not occurs even the MB was kept for the same reaction time but when the system was kept under dark condition in the absence of catalyst the MB converted into methylene violet (MV) after 30 h of reaction.

Synthesis and characterization of Fe3O4 nanoparticles by electrodeposition and reduction methods

Magnetite (Fe3O4) nanoparticles have been studied extensively due to their good magnetic, optic and electric properties which offer a great potential of applications in many field especially in removal of heavy metals such as the adsorption of poisonous Cr(VI) ion in water. In addition, Fe3O4 is the only material that has up to now been use in human because it is the only material which is known to be biocompatible, without relevant toxicity in the applied dosage. In this study Fe3O4 nanoparticles were prepared by reduction of ferric oxide (Fe2O3) precursor at 598 K for 10, 20, 30 and 40 min. While, ferric oxide (Fe2O3) precursor was prepared by electrodeposition of iron plate in the N,N-dimethylformamide solvent and tetraethylammonium perchlorate and naphthalene as mediators at 263 K. Reduction of Fe2O3 was carried out with an isothermal heating at 598 K under hydrogen atmosphere. Fe2O3 and Fe3O4 were characterized with XRD, BET Surface area, FTIR, FESEM-EDX and TEM. The surface area of both Fe2O3 and Fe3O4 was 38 - 45 m2/g with the average particle size was 40 - 60 nm. The XRD result showed that the crystallinity of Fe3O4 increased with reduction time. The activity of Fe2O3 and Fe3O4 nanoparticles were tested on the adsorption of chromium (VI) at room temperature in which 30-40 % of Cr(VI) ion was adsorbed on the Fe2O3 and Fe3O4 nanoparticles.

A facile preparation of nanosized ZnO and its use in photocatalytic decolorization of methyl orange

Nanoparticles zinc metal was prepared by a simple electrochemical method of a N,N-dimethylformamide solution containing 0.1M tetraethylammoniumperchlorate in the presence of naphthalene as a mediator in a one-compartment cell fitted with a platinum plate cathode and a zinc plate anode at 60mA/cm2 of constant current under a nitrogen atmosphere. The prepared zinc oxide (ZnOelec) was characterized by FE-SEM, TEM, XRD, nitrogensorptionand DRUV spectrophotometer, which confirmed that the particles of ZnOelec are composed of pure nanosized ZnO with a large surface area andmajority of particle size was less than 20 nm. The particles size of the ZnOelec affected its photoactivity, which clearly observed when it was tested on adecolorization of methyl orange under UV illumination. By using ZnOelec, 50% of higher removal percentage of MO was achieved compared tocommercial zinc, which only gave 30% after 30 min of contact time. These result shows that ZnOelec has a great potential to be used as a catalyst for thephotocatalytic decolorization of industrial dyes wastewater.

Determination of Lewis and Brönsted acid sites by gas flow-injection technique

Gas flow-injection technique pyridine-FTIR was studied for determination of Lewis and Brönsted acid sites on the solid super acid catalysts. The system consists of stainless steel gas cell which can be heated up to 623 K, CaF2 windows, pyridine injection port and double liquid nitrogen trap for removal of moisture. Pure nitrogen gas and pyridine were used as a carrier and probe molecule. Pyridine was injected to the sysem at 423 K followed by flushing of N2 gas through double liquid nitrogen trap at 423 for 1 h and at 573 K for 30 min. All spectra were recorded at room temperature. This technique gave similar results to those of taken by vacuum system for HZSM-5, Pt/SO4 2--ZrO2, Al2O3 catalysts.

Home-made vacuum system for calculating the apparent density of solid materials

Home-made vacuum system was set up for measuring the apparent density of solid materials or more accurately the volume of solid materials. The volume of samples was calculated based on the method of gas displacement and the inversely proportional relationship between the absolute pressure and volume of a gas known as Boyle's Law, pV=k. Nitrogen gas was used as a probe and the measurement was done at room temperature and at low pressure in order to minimize the effect of the compressibility factor of the gas. The system was calibrated by stainless steel ball with the error was less than 5%. The apparent density of hollow stainless steel (non-porous), rice (irregularly shaped) and Clorets sweet (regularly shaped) were 7.61, 1.60 and 1.23 g/mL, respectively. Whereas the apparent density of porous powdered materials were 1.34, 1.26 and 1.67 g/mL for Pt/SO4 2--Al2O3, WO3-ZrO2 and Portland Cement, respectively. The experimental error for measuring the solid volume was less than 5%.

Photodecolorization of methylene blue over EGZrO2/EGZnO/EGFe2O3/HY photocatalyst: Effect of radical scavenger

The photocatalytic activity of methylene blue (MB) was investigated in aqueous solutions under solar radiation using electrogenerated metals supported on HY zeolite (EGZrO2/EGZnO/EGFe2O3/HY) catalyst. The prepared catalysts were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunnauer-Emmett-Teller surface area analysis (BET). An amount of 0.375 g L−1 EGZrO2/EGZnO/EGFe2O3/HY was found to be the optimum dosage for 10 mg L−1 MB, which gave almost complete photodecolorization of MB (99.5%) after 1 h of contact time at pH 9. Next, the effect of inorganic salts such as NaCl, Na2CO3, Na2SO4, and KI was also studied. It was found that the presence of the Cl− and CO3−2 ions obstructed the photodecolorization, but the presence of SO42− accelerated the reaction. The presence of I− ions did not affect much on the decolorization rate. Furthermore, the addition of H2O2 significantly enhanced the photodecolorization for the 50 mg L−1 of MB solution under similar optimum conditions. It was also found that the radical scavenging agents such as dimethyl sulfoxide (DMSO) and methanol (MeOH) suppressed the decolorization, with DMSO being the most effective. The simple preparation of the photocatalyst and low amount of metal loading required exhibits the great potential of the system that could be applied in textile or other industries wastewater treatment.

Effect of iridium loading on the formation of protonic acid sites over Ir/Pt-HZSM5

The Ir/Pt-HZSM5 with different iridium loading (0.3-1.0 wt%) was prepared by impregnation of iridium on Pt-HZSM5. The acidic properties of Ir/Pt-HZSM5 were studied by FTIR spectroscopy, while the activity of the catalysts was tested for n-pentane isomerization in a microcatalytic pulse reactor.The IR results of adsorbed 2,6-lutidine showed that all catalysts possessed strong Brönsted and Lewis acid sites in the outgassing at 473 K and below.When Ir/Pt-HZSM5 was heated in hydrogen, protonic acid sites were formed with concomitant decrease of Lewis acid sites. An increase in iridiumloading continuously decreased the Lewis and Brönsted acid sites and inhibited the formation of protonic acid sites induced by hydrogen. The formationof protonic acid sites induced by hydrogen was also confirmed by the formation of electron detected by ESR spectroscopy. Additionally for n-pentaneisomerization, an increase in iridium loading decreased the yield of isopentane due to the inhibition in the formation of protonic acid sites via hydrogenspillover phenomenon.

Utilization of bivalve shell-treated Zea mays L. (maize) husk leaf as a low-cost biosorbent for enhanced adsorption of malachite green

In this work, two low-cost wastes, bivalve shell (BS) and Zea mays L. husk leaf (ZHL), were investigated to adsorb malachite green (MG) from aqueous solutions. The ZHL was treated with calcined BS to give the BS-ZHL, and its ability to adsorb MG was compared with untreated ZHL, calcined BS and Ca(OH)(2)-treated ZHL under several different conditions: pH (2-8), adsorbent dosage (0.25-2.5 g L(-1)), contact time (10-30 min), initial MG concentration (10-200 mg L(-1)) and temperature (303-323 K). The equilibrium studies indicated that the experimental data were in agreement with the Langmuir isotherm model. The use of 2.5 g L(-1) BS-ZHL resulted in the nearly complete removal of 200 mg L(-1) of MG with a maximum adsorption capacity of 81.5 mg g(-1) after 30 min of contact time at pH 6 and 323 K. The results indicated that the BS-ZHL can be used to effectively remove MG from aqueous media.

Adsorption of methyl orange from aqueous solution onto calcined Lapindo volcanic mud

In this study, calcined Lapindo volcanic mud (LVM) was used as an adsorbent to remove an anionic dye, methyl orange (MO), from an aqueous solution by the batch adsorption technique. Various conditions were evaluated, including initial dye concentration, adsorbent dosage, contact time, solution pH, and temperature. The adsorption kinetics and equilibrium isotherms of the LVM were studied using pseudo-first-order and -second-order kinetic equations, as well as the Freundlich and Langmuir models. The experimental data obtained with LVM fits best to the Langmuir isotherm model and exhibited a maximum adsorption capacity (q(max)) of 333.3 mg g(-1); the data followed the second-order equation. The intraparticle diffusion studies revealed that the adsorption rates were not controlled only by the diffusion step. The thermodynamic parameters, such as the changes in enthalpy, entropy, and Gibbs free energy, showed that the adsorption is endothermic, random and spontaneous at high temperature. The results indicate that LVM adsorbs MO efficiently and could be utilized as a low-cost alternative adsorbent for the removal of anionic dyes in wastewater treatment.

Complete electrochemical dechlorination of chlorobenzenes in the presence of various arene mediators

Electrochemical dechlorination of chlorobenzenes in the presence of various arene mediators such as naphthalene, biphenyl, phenanthrene, anthracene, and pyrene, was studied. The amount of mediator required was able to be reduced to 0.01 equiv. for all mediators except for anthracene, with the complete dechlorination of mono-, 1,3-di- and 1,2,4-trichlorobenzene still achieved. This catalytic amount of mediator plays an important role in accelerating the dechlorination through the rapid formation of radical anions prior to reduction of the chlorobenzenes.

Complete electrochemical dechlorination of chlorobenzenes in the presence of naphthalene mediator

Electrochemical dechlorination of chlorobenzene in organic solutions was studied. Electrolysis of chlorobenzene in acetonitrile solution in a one-compartment cell fitted with a platinum cathode and a zinc anode at 60mA/cm(2) and 0 degrees C was found to be the optimum conditions, which gave complete dechlorination of chlorobenzene. However, similar result could not be achieved when applying these conditions to 1,3-dichlorobenzene and 1,2,4-trichlorobenzene. We found that the use of naphthalene which reacted as a mediator in the appropriate system could accelerate the reduction and gave complete dechlorination of those chlorobenzenes. Moreover, in the presence of naphthalene the reaction time could be shortened by half compared to dechlorination in the absence of naphthalene.